1. Field of the Invention
This invention relates, for example, to an image pickup apparatus such as an electronic camera and an image pickup method applied thereto.
2. Description of Related Art
There have heretofore been made various propositions regarding the focus control of the zoom lens of a camera. They will be briefly described hereinafter with reference to FIGS. 13 and 14 of the accompanying drawings.
FIG. 13 shows the manner in which a conventional two-unit type zoom lens is operated from a wide state to a telephoto state.
In FIG. 13, the reference numeral 101 designates a one-unit lens, and the reference numeral 102 denotes a two-unit lens. In FIG. 14, each lens position indicated by W on the left side shows a wide (wide angle) state. Each lens position indicated by T on the right side shows the tele(telephoto) state. The reference numeral 103 designates a line indicating the operation locus of the one-unit lens 101. The reference numeral 104 denotes a line indicating the operation locus of the two-unit lens 102.
The fore lens focus type as shown in FIG. 13 is generally known. That is, it is a two-unit zoom type zoom lens. This has focus controlling means for being focused on an object distance. This can be axially moved by an amount corresponding to the object distance, e.g. to a position as indicated by 105 in FIG. 13.
Also, there has been proposed a step zoom lens barrel of a construction in which a focusing operation is adapted to be performed in the course of a zooming operation. This will be described with reference to FIG. 14. This corresponds to Japanese Patent Application Laid-Open No. 3-248110, Japanese Patent Application Laid-Open No. 6-313831, etc.
In FIG. 14, the reference numerals 106 and 107 designate lines indicating the operation loci of the one-unit lens and the two-unit lens, respectively, and the respective lenses are not shown.
A line denoted by the reference numeral 108 is the original operation locus of the two-unit lens. Describing the operation at the wide end indicated by W on the left side in FIG. 14, a zoom lens barrel is operated for focus control during photographing, and therewith, the one-unit lens is axially moved along the line of the operation focus indicated by 106. At this time, the two-unit lens is on the horizontal portion of the line indicating the operation locus 107 and therefore, is not axially moved. The one-unit lens alone is axially moved. Thereby, focus control corresponding to the object distance is effected in the wide state.
Also, during a zooming operation, the zoom lens barrel is axially moved to intermediate positions indicated by M1 and M2 and a tele position indicated by T. Regarding also the focus control at each zoom position, an operation similar to that in the aforedescribed wide state is performed.
In the conventional fore lens focus type shown in FIG. 13, however, there has been a problem as shown below. That is, a driving mechanism or an actuator for operating the one-unit lens besides the two-unit lens has become necessary, and there have been the possibility of the const rising due to an increase in the number of parts, and the possibility of the camera itself becoming bulky.
Also, in the conventional step zoom type shown in FIG. 14, the stop position control of the zoom lens barrel must be effected accurately and therefore, accurate position detection or the like during the operation has been necessary. Thus, a control circuit concerned in position detection has become complicated, and this has led to the possibility of the cost rising.
Further, Japanese Patent Application Laid-Open No. 8-94907 is shown as another example of the prior art. In this publication, there is also proposed a construction in which the step zoom type has respective waiting positions at respective zoom positions and a lens is moved from the respective waiting positions and further between infinity and a close range. Again in this example of the prior art, the stop position control of the zoom lens barrel during photographing must be effected accurately, and a control circuit has become complicated, and this has led to the possibility of the cost rising.